The present invention is directed to bicycles and, more particularly, to various features of an apparatus for controlling a bicycle transmission.
In recent years, some bicycle transmissions have been controlled by devices that operate via electric power or pneumatic power. Such transmissions may be shifted automatically according to the bicycle speed or manually by the rider. Typically, a shift command is generated according to the bicycle speed obtained by a speed sensor or according to manual input by the rider, the shift command is processed by a gear shift controller, and the appropriate gear of the transmission is set by a gear shift unit.
Shift commands sometimes are generated while the gear shift unit is being operated, either manually by the rider or automatically when the bicycle speed changes quickly. When prior art systems receive shift commands at this time, either the shift commands are ignored by the gear shift controller, or else the shift commands are saved and executed sequentially by the gear shift controller after the current gear shift operation has completed. If shift commands are ignored in the case of manual shifting, then the rider""s intentions are not carried out. Furthermore, in such a system the rider must personally keep track of the timing when shifting operations begin and end before he or she can repeat the desired shift command, which makes the shifting operation more complicated. On the other hand, when the shift commands are saved and executed sequentially after the pending gear shift operation has completed, there is a risk of wasted effort. Generally, there is not much difficulty if the series of shift commands correspond to all upshift commands or all downshift commands. However, sometimes the rider enters a mixed series of upshift and downshift commands, either because of changing conditions or because of initial misjudgment of the desired gear. If, for example, the rider wanted to enter a single upshift command but mistakenly entered two upshift commands and then entered a downshift command to correct the error, then in prior art systems the transmission would make a total of three shifts instead of one (two upshift operations and then one downshift operation to achieve the desired gear). Such a mode of operation creates unnecessary wear on the components, it requires more time to execute all of the shift commands, and it unnecessarily drains the power supply.
One possible method to alleviate some of the foregoing problems is to calculate the target gear that would result if all of the shift commands were executed sequentially, and then shift to the resulting target gear after the pending gear shift operation has completed. However, waiting until the pending gear shift operation has completed may cause the new gear shift operation (which is the result of multiple shift commands) to be executed in a rough manner.
The present invention is directed to inventive features of an apparatus for controlling a bicycle transmission. In one embodiment of the present invention, a gear shift control apparatus comprises a shift command input that receives shift commands indicating a desired gear shift operation, a control output that outputs control signals that control a gear shift unit to shift the bicycle transmission, a gear shift monitor that monitors a progress of a gear shift operation by the gear shift unit, and a gear shift controller operatively coupled to the shift command input, to the control output, and to the gear shift monitor. The gear shift controller receives a shift command and outputs a control signal that controls the operation of the gear shift unit to shift the bicycle transmission to a target gear. The gear shift controller modifies the control signal when the gear shift controller receives a second shift command corresponding to a second target gear that differs from a first target gear corresponding to a first shift command and the gear shift operation initiated by the first shift command has not completed. Additional inventive features will become apparent from the description below, and such features alone or in combination with the above features may form the basis of further inventions as recited in the claims and their equivalents.